Electric conductor coated with the reaction product of a dibasic polycarboxylic acid and tris(2-hydroxyethyl) isocyanurate together with an organic polyisocyanate or an alkyl titanate



United States Patent ELECTRIC CONDUCTOR COATED WITH THE RE- ACTIONPRODUCT OF A DIBASIC POLYCAR- BOXYLIC ACID AND TRIS(2-HYDROXYETHYL)ISOCYANURATE TOGETHER WITH AN ORGAN- IC POLYISOCYANATE OR AN ALKYLTITANATE John F. Meyer and Edmund J. Zalewski, Schenectady, N.Y.,assignors to Schenectady Chemicals, Inc., Schenectady, N.Y., acorporation of New York No Drawing. Continuation of application Ser. No.327,041, Nov. 29, 1963. This application Mar. 18, 1965, Ser. No. 440,923

9 Claims. (Cl. 117232) The present application is a continuation ofapplication Serial No. 327,041, filed November 29, 1963, now abandoned,which is a division of application Serial No. 117,- 499, filed June 16,1961.

Thisinvention relates to esters of tris(2-hydroxyethyl) isocyanurate andelectrical conductors coated therewith.

It is an object of the present invention to prepare novel esters oftris(2-hydroxyethyl) isocyanurate.

Another object is to provide improved polyester coatings for electricalconductors.

A further object is to provide wire enamels which exhibit exceptionallygood resistance to heat aging.

Still further objects and the entire scope of applicability of thepresent invention will become apparent from the detailed descriptiongiven hereinafter; it should be understood, however, that the detaileddescription and specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only,since various changes and modifications within the spirit and scope ofthe invention will become apparent to those skilled in the art from thisdetailed description.

It has now been found that these objects can be attained by reactingtris(2-hydroxyethyl) isocyanurate with terephthalic acid or isophthalicacid or an ester forming derivative of such acids. Tris(2-hydroxyethyl)isocyanurate has the formula CHzCHzOH The tris(2-hydroxyethyl)isocyanurate can be employed as the sole polyhydric alcohol or it can bereplaced in part by one or more other polyhydric alcohol-s. While aslittle as 10% of the total polyhydric alcohol can be the tris(2-hydroxyethyl) isocyanurate, preferably at least 50% of the totalpolyhydric alcohol is the isocyanurate on a weight basis..

On an equivalent percent basis preferably at least 25% of the totalpolyhydric alcohol is the tris(2-hydroxyethyl) isocyanurate.

In making the polyester usually to 46 equivalent percent is thecarboxylic acid reactant and the balance is the polyhydric alcohol,i.e., there should be an excess of alcoholic groups over acid groups.

All ofvthe polycarboxylic acid constituent can be the terephthalic acidor isophthalic acid or a portion up to 80 equivalent percent based on atotal of 100 equivalent percent of the acid constituent can be adifferent acid. Preferably at least 50 equivalent percent of the acidcomponent is terephthalic acid. The term equivalent percent isconventionally employed in the art since the alcohol and acid componentsreact on an equivalent rather than a molar basis. The term equivalentpercent is defined for example in Shelter Patent No. 2,889,304 andPrecopio Patent No. 2,936,296.

When a modifying polyhydric alcohol is employed, it can be ethyleneglycol; glycerine; pentaerythritol; 1,1,1- trimethylolethane; 1,1,1trimethylolpropane; sorbitol; mannitol; dipentaerythritol; a,w-aliphatichydrocarbon diols having 4 to 5 carbon atoms, e.g., butanediol-l,4;pentanediol-l,5; butene-2-diol-1,4; and butyne-2-diol-l,4 and cyclicglycols e.g., 2,2,4,4-tetramethyl-1,3-cyclobutanediol, hydroquinone dibeta hydroxyethyl ether and 1,4-cyclohexanedimethanol.

As the acid reactant there is employed terephthalic acid or isophthalicacid or acyl halides thereof, e.g., terephthaloyl dichloride or a lowerdiakyl ester thereof, e.g., methyl, ethyl, propyl, butyl, amyl, hexyland octyl terephthalates and the corresponding isophthalates as well asthe half esters, e.g., monomethyl terephthalates as well as mixtures ofsuch esters and acids or acid halides. Preferably dimethyl terephthalateis employed:

When a modifying polycarboxylic acid is employed, it can be eitheraliphatic or aromatic. Typical examples are adipic acid, ortho phthalicanhydride, hemimellitic acid, trimesic acid, trimellitic acid, succinicacid, tetrachloro phthalic anhydride, hexachloroendomethylenetetrahydrophthalic acid, maleic acid, 'sebacic acid, etc.

To improve abrasion properties of the wire enamel, small amounts ofmetal driers are employed.

While the new polyesters are preferably employed in making wire enamels,they are also useful in making molded products and in solution can beused to impregnate cloth, paper, asbestos and the like. They can beemployed in general wherever alkyd resins are useful.

The total number of hydroxyl groups on the alcohols normally is 1 to 1.6times the total number of carboxyl groups on the acids. T

It has further been found that the properties of the polyester can beimproved by the addition of a polyisocyanate in an amount of 10 40%,preferably 15 to 25 by weight of the total of the polyisocyanate andpolyester.

Preferably, the polyisocyanate has at least three available isocyanategroups.

Among the polyisocyanates which can be employed there may be mentioneddiisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylenediisocyanates, cyclopentylene diisocyanate, m-phenylene diisocyanate,p-phenylene diisocyanate, ethylene diisocyanate, butylidenediisocyanate, 1,5-naphthalene diisocyanate, 1,6-hexamethylenediisocyanate, dianisidine diisocyanate, 4,4'-diphenyl ether di-1isocyanate, 4,4'4"-tr=iphenyl methane triisocyanate (Desmodur R), thecyclic trimer of 2,4-tolylene diisocyanate,

1 the cyclic trimer of 2,6-tolylene diisocyanate, mixtures of the cyclictrimers of 2,4-tolylene diisocyanate and 2,6- tolylene diisocyanate, thetrimer of 4,4'-diphenyl methane diisocyanate, trifunctional isocyanatetrimers having the formula:

' O=C\ :0 N

Where R is a lower alkyl radical, e.g., n butyl, tertiary butyl,secondary butyl, isopropyl, methyl, ethyl, etc., 1,3, S-triisocyanatobenzene, 2,4,6-triisocyanato toluene, 4,4- dimethyl-d'iphenylmethane,2,2',5,5-tetrais0cyanate, 2,4,

4'-trii-socyanato diphenylmethane, 2,4,6-triisocyanato diphenyl ether,2,2',4-triisocyanato diphenyl ether, 2,24- triisocyanato diphenylsulfide, 2,4,4-triisocyanato diphenyl sulfide,2,3',4-triisocyanato-4'-methyl diphenyl ether,2,3',4-triisocyanato-4'-methoxydiphenyl ether, 2,4,4-triisocyanato-3'-chlorodiphenyl ether,2,4,4'-triisocyanato-3',5-dimethyl diphenyl ether, 4,4,6-diphenyltriisocyanate, 1,2,4-butanetriol triisocyanate, 1,3,3-pentanetriisocyanate, 1,2,2-butane triisocyanate, phloroglucinol triisocyanate,the reaction product of 3 mols of 2,4-tolylene diisocyanate with 1 molof trimethylol propane, the reaction product of 3 mols of 2,6-tolylenedi-isocyanate with 1 mol of trimethylol propane, the reaction product of3 mols of 2,4-tolylene diisocyanate with 1 mol of trimethylol propane,the reaction product of 3 mols of 2,4-tolylene diisocyanate with 1 molof trimethylol ethane and, in general, the reaction product of adiisocyanate with sufiicient polyhydric alcohol to react with half theisocyanate groups.

While the polyisocyanates can be used as such, particularly where potlife is not important, it is preferred to block the isocyanate groupingswith a group that will split off at the reaction temperature employedwith the polymeric terephthalic or is'ophthalic ester. Typical compoundswhich can be used to block the isocyanate groupings, e.g., by formingcarbamates therewith, are mono hydric phenols, such as phenol,meta-cresol, para-cresol, ortho-cresol and mixtures thereof, thexylenols, e.g., 2,6- dimethyl phenol, 4-ethyl phenol, 4-tertiary butylphenol, 2-butyl phenol, 4-n-octyl phenol, 4-isooctyl phenol, 2- chlorophenol, 2,6-dichloro phenol, 2-nitro-phenol, 4- nitro phenol, 3-nitrophenol, monohydric alcohols such as methyl alcohol, ethyl alcohol,n-propyl alcohol, isopropyl alcohol, tertiary butyl alcohol, tertiaryamyl alcohol, octyl alcohol, stearyl alcohol, acet'oacetic ester,hydroxyalkylcarbamic acid aryl esters, e.g., hydroxyethylcarbamic acidphenyl ester, hydroxyethylcarbamic acid cresyl ester, diethyl malonate,mercaptans, e.g., 2-mercaptobenzothiazole, Z-mercaptothiazoline, dodecylmercaptan, ethyl Z-mercaptothiazole, p-naphthyl mercaptan, ocnaphthylmercaptan, methyl 'mercaptan, butyl mercaptan, lactams, e.g.,e-caprolactam, A-valerolactam, 'y-butyrolactam, ,B-propiolacta-m,imides, e.g., succinimide, phthalimide, .naphthalimide, glutarimide,dimethylphenyl car- -binol, secondary amines, e.g., o-ditolyamine,m-ditolylamine, p-ditolylamine, N-phenyl toluidine,phenyl-a-naphthylamine, carbazole, diphenylamine, etc.,mono-a-phenylethyl phenol, di-a-phenylethyl phenol, tri-u-phenylethylphenol, carvacrol, thymol, methyl diphenyl carbinol, triphenyl carbinol,l-nitro tetiary butyl carbinol, 1-chlorotertiary butyl carbinol,triphenyl silanol, 2,2'-dinitrodi phenylamine,2,2-dichloro-diphenylamine, ethyl n-butyl malonate, ethyl .benzylmalonate, acetyl acetone, acetonyl acetone, benzimidazole,1-phenyl-3-methyl-5-pyrazolone.

As specific examples of such blocked polyisocyanates, there may bementioned Mondur S, wherein the isocyanate groups of the reactionproduct of 3 mols of mixed 2,4- and 2,6-tolylene diisocyanate withtrimethylol propane are blocked by esterification with m-cresol. Atpresent Mondur SH is the preferred polyisocyanate.

Other blocked polyisocyanates include the cyclic trimer of 2,4-tolylenediisocyanate having the isocyanate groups blocked with tertiary butylalcohol or tertiary amyl alcohol or dimethyl ethinyl carbinol oraceto-acetic acid ester or phenol or cresylic acid or e-caprolactam or2-mercaptoben zothiazole or succinimide or phthalimide or diphenyl amineor phenyl-B-naphthyl amine, triphenyl methane triisocyanate having theisocyanate groups blocked with phenol or mixed cresols or tertiary butylalcohol or phthalimide, 1,3,3-pentanetriisocyanate having the isocyanategroups blocked with m-cresol, etc.

Unless otherwise stated hereinafter in the specification and claims, itis understood that whenever the term polyisocyanate is employed, it isintended to include both the free isocyanates and the blockedisocyanates.

The polyisocyanate is mixed with the preformed polyester either dry ordissolved in a solvent prior to mixing. The reaction between thepolyester and the polyisocyanate is hastened by using elevatedtemperatures and in preparing wire enamels they are usually reacted at atemperature of about 650 to 800 F.

The metal drier is preferably used in an amount of 0.2 to 1.0% metalbased on the total solids in the enamel. Typical metal driers includethe zinc, lead, calcium or cadmium linoleates, octoates, and resinatesof each of these metals, e.g., zinc resinate, cadmium resinate, leadlinoleate, calcium linoleate, zinc naphthenate, lead naphthenate,calcium naphthenate, cadmium naphthenate, zinc octoate and cadmiumoctoate. Other suitable metal driers, specifically polyvalent metaldriers such as manganese naphthenate and cobalt naphthenate can beemployed.

It has further been found that the properties of the polyester wireenamel can be improved by incorporating a tetraalkyl titanate in placeof the metal drier and polyisocyanate. Typical tetraalkyl titanates aretetraisopropyl titanate, tetrabutyl titanate, tetrahexyl titanate,tetramethyl titanate and tetrapropyl titanate. The titanate is used insmall amounts, e.g., 0.001 to 4.0% titanium metal on the total solids ofthe enamel.

The use of tris(2-hydroxyethyl) isocyanurate gives wire enamels whichexhibit exceptionally good resistance to heat aging as shown byexperiments carried out at 240 C.

The solvent employed in making the wire enamel is cresylic acid.Cresylic acid has a boiling range of 185 to 230 C. and is a mixture ofo-, m-, and p-cresols. The individual cresols, e.g., para-cresol,meta-cresol or orthocresol can be employed although it is preferred touse the commercial cresylic acid mixture.

It is frequently desirable to dilute the cresylic acid with i anaromatic hydrocarbon, e.g., a heavy coal tar or petroleum naphtha orwith xylene, etc. The naphtha can be employed in an amount of from 0 to60%, e.g., 5 to 60%, based on the total weight of the solvents:preferably, the naphtha. Various conventional aromatic naphthas,especially high boiling naphthas can be employed such as EW naphtha (anenamel wire heavy coal tar naphtha sold by the Barrett Division ofAllied Chemical and Dye Corporation) and Solvesso No. 100, an aromaticnaphtha derived from petroleum.

The temperature of reaction is not especially critical and temperaturesconventionally employed in peparing known glycerine or ethylene glycolesters of terephthalic acid are used, e.g., C. to reflux temperature.

The wire enamel is applied to the wire, e.g., copper wire, by either thefree dip or the die application procedure. In the following specificexamples the die application procedure was employed to obtain a build upof approximately 3 mils on #18 A.W.G. copper wire.

The tests employed on the coated wire for the most part are described inPrecopio Patent 2,936,296 and are conventional in the wire enamel art.The high temperature dielectric twist aging test was carried out at 240C. rather than under the less severe conditions set forth in thePrecopio patent.

Unless otherwise stated, all parts and percentages are by weight.

Example 1 Ethylene glycol grams 147 Glycerine do 97 1,4-butanediol do 74Tris(2-hydroxyethyl) isocyanurate do 608 Dimethyl terephthalate do 1164Litharge (catalyst) do 0.3 Solvesso 100 ml 224 Xylol ml 100 The abovemixture was reacted at a temperature of 430-435 F. until a hydroxylvalue of 154.5 was reached. The product was then reduced to 50.6% solidswith cresylic acid to produce product A.

Wire Speed 27 ftJmin. 32 ft./rn in.

Cut Through, C 272-308 260-310 Heat Shock, 175 0., 1x-2x-3x 100100-10020-90-100 Dielectric Twist Heat Aging, 1,000 volts at 240 0., hrs 1, 6001, 088

Example 2 2,2,4,4-tetramethyl 1,3-cycl0butanediol grams 119.6 Tris(2-hydroxyethyl) isocyanurate do 7 51 1 Ethylene glycol do 129 Glycerinedo 128 Dimethyl terephthalate do 1 112.8 Litharge do 0.4 Xylol mL 86Solvesso 100 ml 258 This mixture was reacted using an azeotropicdistillation at a temperature of 490500 F. until a hydroxyl value of 136was reached. The batch was then reduced to 50.9% solids with cresylicacid to produce product B.

A wire enamel was then made from 812 grams of product B, 116 grams ofMondur SH, 402 grams of cresylic acid, 432 grams of Solvesso 100 and29.4 grams of 9% zinc octoate in E.W. naphtha. The wire enamel producedthe following properties on 18 gauge copper wire,

1 Wire Speed 27 ftJmin. 32 ft./min.

Cut Through, C 320-830 320-300. Heat Shock at 175 0., 1x-2x-3x 10010010070100100. Dielectric Twist Heat Aging at 240 C In excess of In excess of2,000 hrs. 1,700 hrs.

Example 3 The process of Example 1 was repeated but the heating at430-435 F. was continued until the hydroxyl value was 124. This productwas reduced to 51% solids with cresylic acid and labeled product C.

1000 grams of product C, 458 grams of Solvesso 100 and 20.4 grams oftetraisopropyl titanate were made up as a wire enamel and coated on 18gauge copper wire. The cut through temperature was 355-360 C. at wirespeeds of from 27 feet/min. to 32 feet/min.

Example 4 Tris(2-hydroxyethyl) isocyanurate 1044 grams (4 moles).Dimethyl terephthalate 776 grams (4 moles). Xylol 100 ml. Solvesso 100200 ml. Tetraisopropyl titanate 3.6 grams.

When run on #18 AWG copper wire through a commercial wire enamelingtower enameled wire was produced which was eminently satisfactory forcommerical use. Abrasion resistance measured on a General Electricscrape abrasion tester was 57 strokes; flexibility was satisfactory; cutthrough temperature was 385-390 C.; heat shock at 175 C. 1x mandrel 60%pass, 2x mandrel 100% pass, 3x mandrel 100% pass. AIEE No. 57 heat lifetests indicated that the enamel had at least a class B rating.

Example 5 Tris(2-hydroxyethyl) isocyanurate grams 992 Ethylene glycol do88 Dimethyl terephthalate do 920 Litharge do 0.3 Xylol ml 100 Solvesso100 ml 200 The above mixture was charged into the same reaction vesselas that used in Example 4. The batch was slowly heated during 8 hoursuntil a temperature of 440 F. was attained. Cresylic acid was then addedto yield a solids content of 67.2%. 1000 grams of the above materialwere mixed with 680 grams of cresylic acid, 1008 grams of Solvesso 100and 26.9 grams of tetraisopropyl titanate. The resulting enamel had aviscosity of C. (Gardner-Holdt) and a solids content of 25%. When run on#18 AWG copper wire the enameled wire obtained was typical of goodcommercial wire. The scrape was above 30; flexibility was satisfactory;cut through was in the range of 385-395 C.; heat shock at 175 C. 1xmandrel pass, 2x mandrel pass, 3x mandrel 100%. AIEE No. 57 heat lifetests indicated that the material would be at least a class B enamel.

Example 6 Tris(Z-hydroxyethyl) isocyanurate grams 556 Dimethylterephthalate do 413 Adipic acid d0 31 Litharge do 0.15 Xylol ml 50Solvesso 100 ml 100 The above mixture was charged into the reactionvessel. The batch was slowly heated over the course of 8 hours until atemperature of 465 F. was reached. At

this time the batch was reduced with cresylic aciduntil a solids contentof 50.5% was obtained. To 1000 grams of the above material were added262 grams of cresylic acid and 758 grams of Solvesso 100 and 20.2 gramsof tetraisopropyl titanate. The wire enamel obtained had a viscosity ofA (Gardner-Holdt and a solids content of 25 When run on #18 AWC copperwire in a wire enameling tower, commercially acceptable wire wasobtained.

What is claimed is:

1. An electrical conductor provided with a continuous coating comprisingthe reaction product of a polymeric ester of a polycarboxylic acid ofthe group consisting of terephthalic acid and isophthalic acid andtris(2-hydroxyethyl) isocyanurate with 10 to 40% of an organicpolylsocyanate.

2. An electrical conductor provided with a continuous coating comprisingthe reaction product of a polymeric ester of a polycarboxylic acid ofthe group consisting of terephthalic acid and isophthalic acid andtris(2-hydroxyethyl) isocyanurate with 0.001 to 4.0% of an alkyltitanate.

3. An electrical conductor according to claim 2 wherein in the polymericester a portion of the tris(2-hydroxyethyl) isocyanurate up to 50equivalent percent of the total polyhydric alcohol is replaced byanother polyhydric alcohol.

4. An electrical conductor according to claim 3 wherein the otherpolyhydric alcohol is ethylene glycol.

5. An electrical conductor according to claim 1 wherein in the polymericester a portion of the tris(2-hydroxyethyl) isocyanurate up to 0equivalent percent of the total polyhydric alcohol is replaced byanother poly hydric alcohol.

6. An electrical conductor according to claim 5 Wherein the otherpolyhydric alcohol is ethylene glycol.

7. An electrical conductor provided with a continuous coating comprisingthe reaction product of a polymeric ester of a polycarboxylic acid ofthe group consisting of terephthalic acid and isophthalic acid andtris(2-hydroxyethyl) isocyanurate with an alkyl titanate in an amount togive 0.001 to 4.0% titanium metal.

8. An electrical-conductor according to claim 7 wherein in the polymericester a portion of the tris(2-hydroxyethyl) isocyanurate up to 50equivalent percent of the total polyhydric alcohol is replaced byanother polyhyd'ric alcohol.

9. An electrical conductor according to claim 8 wherein the otherpolyhydric alcohol is ethylene glycol.

No references cited.

JOSEPH B. SPENCER, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 211,585 October 12 1965 John F. Meyer et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 7, line 3, for "0" read 5O Signed and sealed this 3rd day of May1966.

( L) Attest:

ERNEST w. SWIDER EDWARD J. BRENNER \ttesting Officer Commissioner ofPatents

1. AN ELECTRICAL CONDUCTOR PROVIDED WITH A CONTINUOUS COATING COMPRISINGTHE REACTION PRODUCT OF A POLYMERIC ESTER OF A POLYCARBOXYLIC ACID OFTHE GROUP CONSISTING OF TEREPHTHALIC ACID AND ISOPHTHALIC ACID ANDTRIS(2-HYDROXYETHYL) ISOCYANURATE WITH 10 TO 40% OF AN ORGANICPOLYISOCYANATE.